Integrated fan-out package

ABSTRACT

An integrated fan-out package includes a first redistribution structure, a die, an insulation encapsulation, and a second redistribution structure. The die is disposed on the first redistribution structure. The insulation encapsulation encapsulates the die. The second redistribution structure is disposed on the die and the insulation encapsulation. At least one of the first redistribution structure and the second redistribution structure includes a dielectric layer, a feed line, and a signal enhancement layer. The feed line is at least partially disposed on the dielectric layer. The signal enhancement layer covers the feed line. The signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the dielectric layer.

BACKGROUND

Semiconductor devices and integrated circuits used in a variety of electronic apparatus, such as cell phones and other mobile electronic equipment, are typically manufactured on a single semiconductor wafer. The dies of the wafer may be processed and packaged with other semiconductor devices (e.g. antenna) or dies at the wafer level, and various technologies have been developed for the wafer level packaging.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic top view illustrating an integrated fan-out package according to some embodiments of the present disclosure.

FIG. 2A to FIG. 2J are schematic cross-sectional views illustrating various stages in a manufacturing method of the integrated fan-out package along line A-A′ in FIG. 1.

FIG. 3 is a schematic cross-sectional view illustrating an integrated fan-out package according to some alternative embodiments of the present disclosure.

FIG. 4 is a schematic cross-sectional view illustrating an integrated fan-out package according to some alternative embodiments of the present disclosure.

FIG. 5A to FIG. 5J are schematic cross-sectional views illustrating various stages in a manufacturing method of an integrated fan-out package according to some alternative embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Other features and processes may also be included. For example, testing structures may be included to aid in the verification testing of the 3D packaging or 3DIC devices. The testing structures may include, for example, test pads formed in a redistribution layer or on a substrate that allows the testing of the 3D packaging or 3DIC, the use of probes and/or probe cards, and the like. The verification testing may be performed on intermediate structures as well as the final structure. Additionally, the structures and methods disclosed herein may be used in conjunction with testing methodologies that incorporate intermediate verification of known good dies to increase the yield and decrease costs.

FIG. 1 is a schematic top view illustrating an integrated fan-out package 10 according to some embodiments of the present disclosure. FIG. 2A to FIG. 2J are schematic cross-sectional views illustrating various stages in a manufacturing method of the integrated fan-out package 10 along line A-A′ in FIG. 1. Referring to FIG. 1A, a carrier C is provided. In some embodiments, the carrier C is a glass substrate. Subsequently, a dielectric layer 102 a, a first conductive pattern layer 104, and a dielectric layer 102 b are sequentially formed on the carrier C. In some embodiments, the dielectric layers 102 a and 102 b are made of the same material, so the dielectric layers 102 a and 102 b are collectively referred to as a first dielectric layer 102. In some embodiments, the first dielectric layer 102 may be a polymer layer made of polybenzoxazole (PBO), polyimide (PI), benzocyclobutene (BCB), a combination thereof, or the like. The first conductive pattern layer 104 includes a ground plane GP and a plurality of first feed lines FL1. In some embodiments, the ground plane GP may be electrically connected to a ground. On the other hand, the feed lines FL1 may be electrically connected to other subsequently formed conductive elements for signal transmission. The ground plane GP and the first feed lines FL1 may be formed by a same photolithography process at the same time. In some embodiments, the first conductive pattern layer 104 includes copper, nickel, titanium, a combination thereof, or the like. As illustrated in FIG. 2A, in some embodiments, the ground plane GP is substantially embedded in the first dielectric layers 102. On the other hand, the dielectric layer 102 b has a plurality of trenches T which expose the first feed lines FL1. In other words, the first feed lines FL1 are disposed on the first dielectric layer 102 (i.e. the dielectric layer 102 a) and are not covered by the first dielectric layer 102. In some embodiments, a de-bonding layer (not shown) may be provided between the first dielectric layer 102 and the carrier C. The de-bonding layer may be a light-to-heat conversion (LTHC) release layer and may aid the removal of the carrier C in the subsequent processes. It should be noted that the number of the dielectric layers 102 a, 102 b and/or the first conductive pattern layer 104 is not limited by the illustration presented in FIG. 2A. In some alternative embodiments, more dielectric layers and/or more conductive pattern layers may be formed to stack alternately.

A plurality of first through interlayer vias (TIV) 200 a are formed on the first feed lines FL1 exposed by the trenches T of the dielectric layer 102 b. In some embodiments, the method of forming the first TIVs 200 a includes the following steps. A seed material layer (not shown) is formed over the first feed lines FL1. In some embodiments, the seed material layer includes a titanium/copper composite layer, and is formed by a sputtering process. Thereafter, a photoresist layer (not shown) with openings is formed on the seed material layer, and the openings of the photoresist layer expose the intended locations for the subsequently formed TIVs. Afterwards, a plating process is performed to form a metal material layer (e.g., a copper layer) on the seed material layer exposed by the openings of the photoresist layer. The photoresist layer and the underlying seed material layer are then removed to form the first TIVs 200 a.

Referring to FIG. 2B, a signal enhancement layer 106 is filled into the trenches T of the dielectric layer 102 b to cover the first feed lines FL1. In some embodiments, the signal enhancement layer 106 has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the first dielectric layer 102. In other words, the signal enhancement layer 106 and the first dielectric layer 102 are formed of different materials. For example, the signal enhancement layer 106 may include epoxy-based, phenolic-based, aromatic-based, or cyanate ester-based molding compounds, FR4 or low temperature co-fired ceramics (LTCC) substrate-based dielectric materials, or pattern-able dielectric materials such as polybenzoxazole (PBO), polyimide (PI), or benzocyclobutene (BCB). In some embodiments, the signal enhancement layer 106 has the Df ranges between 0.001 and 0.02 and the Dk ranges between 3 and 4. In some embodiments, the first dielectric layer 102, the first conductive pattern layer 104, and the signal enhancement layer 106 may be collectively referred to as a first redistribution structure 100. In some embodiments, the first redistribution structure 100 may be referred to as a backside redistribution structure. The first redistribution structure 100 has a first surface 100 a and a second surface 100 b opposite to the first surface 100 a. At this stage, the first surface 100 a faces upward while the second surface 100 b is attached to the carrier C.

Referring to FIG. 2C, a die 300 (or integrated circuit components) may be picked and placed on the first surface 100 a of the first redistribution structure 100. The die 300, for example, includes a semiconductor substrate 310, a plurality of conductive pads 320, a passivation layer 330, a post passivation layer 340, a plurality of conductive vias 350, and a protection layer 360. In some embodiments, the conductive pads 320 are disposed over the semiconductor substrate 310. The passivation layer 330 is formed over the semiconductor substrate 310 and has contact openings that partially expose the conductive pads 320. The semiconductor substrate 310 may be a silicon substrate including active components (e.g., transistors or the like) and passive components (e.g., resistors, capacitors, inductors or the like) formed therein. The conductive pads 320 may be aluminum pads, copper pads, or other suitable metal pads. The passivation layer 330 may be a silicon oxide layer, a silicon nitride layer, a silicon oxy-nitride layer, or a dielectric layer formed by other suitable dielectric materials. Furthermore, the post-passivation layer 340 is formed over the passivation layer 330. The post-passivation layer 340 covers the passivation layer 330 and has a plurality of contact openings. The conductive pads 320 are partially exposed by the contact openings of the post passivation layer 340. The post-passivation layer 340 may be a polyimide (PI) layer, a polybenzoxazole (PBO) layer, or a dielectric layer formed by other suitable polymers. In addition, the conductive vias 350 are formed on the conductive pads 320. In some embodiments, the conductive vias 350 are plated on the conductive pads 320. The protection layer 360 is formed on the post-passivation layer 340 so as to cover the conductive vias 350.

In some embodiments, the die 300 is attached (or adhered) on the first dielectric layer 102 and the signal enhancement layer 106 through a die attach film (not shown). In some embodiments, one or more die(s) 300 may be picked and placed on the first dielectric layer 102 and the signal enhancement layer 106 after the formation of the first TIVs 200 a. However, the disclosure is not limited thereto. In some alternative embodiments, one or more die(s) 300 may be picked and placed on the first dielectric layer 102 and the signal enhancement layer 106 before the formation of the first TIVs 200 a.

Referring to FIG. 2D, an insulation encapsulation 400 is formed over the first surface 100 a of the first redistribution structure 100 to encapsulate the die 300 and the first TIVs 200 a. In some embodiments, the insulation encapsulation 400 includes a molding compound, a molding underfill, a resin or the like, such as epoxy. In some alternative embodiments, the insulation encapsulation 400 includes a photo-sensitive material such as polybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), a combination thereof, or the like. In some embodiments, the method of forming the insulation encapsulation 400 includes the following steps. First, an insulating material (not shown) is formed on the first dielectric layer 102 and the signal enhancement layer 106 through, for example, a compression molding process so as to encapsulate the die 300 and the first TIVs 200 a. The conductive vias 350 and the protection layer 360 of the die 300 are encapsulated by the insulating material. In other words, the conductive vias 350 and the protection layer 360 of the die 300 are not revealed and are well protected by the insulating material. Thereafter, the insulating material is grinded until the top surfaces of the conductive pillars 350, the top surfaces of the first TIVs 200 a, and the top surface of the protection layer 360 are exposed, so as to form the insulation encapsulation 400. In some embodiments, the insulating material is grinded by a mechanical grinding process and/or a chemical mechanical polishing (CMP) process. In some embodiments, during the grinding process of the insulating material, the protection layer 360 is grinded to reveal the conductive vias 350. In some embodiments, portions of the first TIVs 200 a and portions of the conductive vias 350 are slightly grinded also. After grinding, the die 300 has an active surface 300 a and a rear surface 300 b opposite to the active surface 300 a. The exposed portion of the conductive vias 350 is located on the active surface 300 a of the die 300. In some embodiments, the first feed lines FL1 extend over the rear surface 300 b of the die 300.

Referring to FIG. 2E, a second redistribution structure 500 is formed on the die 300 and the insulation encapsulation 400. As illustrated in FIG. 2E, the active surface 300 a of the die 300 faces the second redistribution structure 500. In some embodiments, the second redistribution structure 500 includes a second dielectric layer 502, a second conductive pattern layer 504, and an under-ball metallurgy (UBM) layer 506. In some embodiments, the second dielectric layer 502 may be constituted by dielectric layers 502 a, 502 b made of a same material. In some embodiments, the second dielectric layer 502 may include the same material as that of the first dielectric layer 102. For example, the second dielectric layer 502 may be a polymer layer made of polybenzoxazole (PBO), polyimide (PI), benzocyclobutene (BCB), a combination thereof, or the like. Similarly, the second conductive pattern layer 504 and the UBM layer 506 may include the same material as that of the first conductive pattern layer 104. For example, the second conductive pattern layer 504 and the UBM layer 506 may include copper, nickel, titanium, a combination thereof, or the like. The second conductive pattern layer 504 is electrically connected to the conductive vias 350 of the die 300 and the first TIVs 200 a embedded in the insulating encapsulation 400. In other words, the first TIVs 200 a electrically connect the first redistribution structure 100 and the second redistribution structure 500. In some embodiments, the topmost second conductive pattern layer 504 may be referred to as the UBM layer 506 for ball mount. In some embodiments, when the second conductive pattern layer 504 is adapted to transmit signal from the die 300 to the first feed line FL1 through the first TIVs 200 a, the second conductive pattern layer 504 may be referred to as a second feed line FL2. As illustrated in FIG. 2E, the dielectric layer 502 a, the first conductive pattern layer 504, the dielectric layer 502 b, and the UBM layer 506 are stacked in sequential order. However, this configuration construes no limitation in the present disclosure. In some alternative embodiments, more dielectric layers and/or more conductive patterns layers may be formed to stack alternately. In some embodiments, the second redistribution structure 500 may be referred to as a front-side redistribution structure.

Referring to FIG. 2F, a plurality of conductive terminals 600 are formed on the second redistribution structure 500. In some embodiments, the conductive terminals 600 are attached to the UBM layer 506 through a solder flux (not shown). In some embodiments, the conductive terminals 600 are, for example, solder balls, ball grid array (BGA) balls, or C4 bumps. In some embodiments, the conductive terminals 600 are made of a conductive material with low resistivity, such as Sn, Pb, Ag, Cu, Ni, Bi, or an alloy thereof. In some embodiments, the conductive terminals 600 may be disposed on the UBM layer 506 by a ball placement process and/or a reflow process.

Referring to FIG. 2G, after the conductive terminals 600 are formed, the structure illustrated in FIG. 2F is flipped upside down and is attached to a tape TP for further processing. As illustrated in FIG. 2G, the carrier C is separated from the second surface 100 b of the first redistribution structure 100. In some embodiments, the de-bonding layer (not illustrated; e.g. LTHC release layer) may be irradiated by UV laser such that the dielectric layer 102 is de-bonded from the carrier C.

Referring to FIG. 2H, an insulating layer 700 is formed over the second surface 100 b of the first redistribution structure 100. In some embodiments, the insulating layer 700 is formed on the dielectric layer 102 a. In some embodiments, the insulating layer 700 is a polymer layer. For example, the insulating layer 700 includes a photo-sensitive material such as polybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), a combination thereof, or the like. In some alternative embodiments, the insulating layer 700 includes epoxy resins or any other suitable type of molding materials. In some embodiments, the material of the insulating layer 700 has low Dk and low Df properties. Depending on the frequency range of high-speed applications, suitable materials of the insulating layer 700 may be selected based on the required electrical properties of the integrated fan-out package 10. The insulating layer 700 is formed by a suitable fabrication technique such as spin-coating, lamination, deposition or the like.

Referring to FIG. 2I, a plurality of conductive patches 800 are formed on the insulating layer 700. In some embodiments, the conductive patches 800 may be electrically coupled to the first feed lines FL1 of the first redistribution structure 100. In other words, the signal transmitted in the first feed lines FL1 may be electrically coupled to the conductive patches 800 such that the conductive patches 800 may be referred to as patch antennas. In some embodiments, the conductive patches 800 are formed by forming a metallization layer (not shown) through electroplating or deposition over the insulating layer 700 and then patterning the metallization layer by photolithography and etching processes. In some alternative embodiments, the conductive patches 800 may be formed by forming a plurality of metallization patterns (not shown) directly through plating processes. In some embodiments, the material of the conductive patches 800 includes aluminum, titanium, copper, nickel, tungsten, and/or alloys thereof.

Referring to FIG. 1 and FIG. 2J, the structure illustrated in FIG. 2I is separated from the tape TP to obtain the integrated fan-out package 10. It should be noted that for simplicity, certain elements in the integrated fan-out package 10 is omitted in FIG. 1. As illustrated in FIG. 1 and FIG. 2J, since the first feed lines FL1 are wrapped around by the signal enhancement layer 106, due to the low dissipation factor and/or the low permittivity nature of the signal enhancement layer 106, the signal loss/decay when transmitting through the first feed lines FL1 may be effectively reduced. As a result, the signal originated from the die 300 may be coupled to the conductive patches 800 with minimum loss, thereby effectively enhancing the efficiency of the integrated fan-out package 10.

FIG. 3 is a schematic cross-sectional view illustrating an integrated fan-out package 20 according to some alternative embodiments of the present disclosure. The integrated fan-out package 20 of FIG. 3 may be manufactured by the steps similar to the steps illustrated in FIG. 2A to FIG. 2J, so similar elements are denoted by the same reference numeral and the detailed descriptions thereof are omitted herein. As illustrated in FIG. 3, the integrated fan-out package 20 further includes a plurality of second TIVs 200 b embedded in the insulation encapsulation 400. The second TIVs 200 b are electrically connected to the second redistribution structure 500. In some embodiments, the second TIVs 200 b may be formed on the dielectric layer 102 b during the step of forming the first TIVs 200 a (the step illustrated in FIG. 2A). For example, the first TIVs 200 a and the second TIVs 200 b may be simultaneously formed. In some embodiments, the second TIVs 200 b are arranged to form a plurality of dipole antennas. In some embodiments, the second TIVs 200 b (dipole antennas) have a dimension (e.g. width) greater than that of the first TIVs 200 a. However, the present disclosure is not limited thereto. In some alternative embodiments, the second TIVs 200 b (dipole antennas) may have a dimension (e.g. width) substantially equal to or less than that of the first TIVs 200 a. As illustrated in FIG. 2, since the first feed lines FL1 are wrapped around by the signal enhancement layer 106, due to the low loss dissipation factor and/or the low permittivity nature of the signal enhancement layer 106, the signal loss/decay when transmitting through the first feed lines FL1 may be effectively reduced. As a result, the signal originated from the die 300 may be coupled to the conductive patches 800 with minimum loss, thereby effectively enhancing the efficiency of the integrated fan-out package 20.

FIG. 4 is a schematic cross-sectional view illustrating an integrated fan-out package 30 according to some alternative embodiments of the present disclosure. The integrated fan-out package 30 of FIG. 4 may be manufactured by the steps similar to the steps illustrated in FIG. 2A to FIG. 2J, so similar elements are denoted by the same reference numeral and the detailed descriptions thereof are omitted herein. As illustrated in FIG. 4, the integrated fan-out package 30 further includes a plurality of second TIVs 200 b embedded in the insulation encapsulation 400. Moreover, in some embodiments, the step of filling the signal enhancement layer 106 into the trenches T of the dielectric layer 102 b as illustrated in FIG. 2B may be omitted. As such, during the step of forming the insulation encapsulation 400 (the step illustrated in FIG. 2D), the insulation encapsulation 400 is filled into the trenches T of the dielectric layer 102 b to constitute the protrusions 402 of the insulation encapsulation 400, as illustrated in FIG. 4. In other words, the protrusions 402 of the insulation encapsulation 400 laterally wrap around the first feed lines FL1 and cover at least part of the rear surface 300 b of the die 300. In some embodiments, the insulation encapsulation 400 has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the first dielectric layer 102. In other words, the insulation encapsulation 400 and the first dielectric layer 102 are formed of different materials. In some embodiments, the insulation encapsulation 400 has the Df ranges between 0.001 and 0.02 and the Dk ranges between 3 and 4. Since the first feed lines FL1 are wrapped around by the insulation encapsulation 400, due to the low dissipation factor and/or the low permittivity nature of the insulation encapsulation 400, the signal loss/decay when transmitting through the first feed lines FL1 may be effectively reduced. As a result, the signal originated from the die 300 may be coupled to the conductive patches 800 with minimum loss, thereby effectively enhancing the efficiency of the integrated fan-out package 30.

FIG. 5A to FIG. 5J are schematic cross-sectional views illustrating various stages in a manufacturing method of an integrated fan-out package 40 according to some alternative embodiments of the present disclosure. Throughout the descriptions with respect to FIG. 5A to FIG. 5J, elements similar to that of the previous embodiments are denoted by the same reference numeral and the detailed descriptions thereof are omitted herein. Referring to FIG. 5A to FIG. 5D, the steps illustrated herein are similar to the steps presented in FIG. 2A to FIG. 2D except for the formation of the second TIVs 200 b. In some embodiments, the second TIVs 200 b may be formed on the dielectric layer 102 b during the step of forming the first TIV 200 a, as illustrated in FIG. 5A. In some embodiments, the second TIVs 200 b are arranged to form a plurality of dipole antennas.

Referring to FIG. 5E, a second dielectric layer 502 is formed on the insulation encapsulation 400 and the active surface 300 a of the die 300 to partially cover the insulation encapsulation 400, the first TIV 200 a, and the second TIVs 200 b. In some embodiments, the insulation encapsulation 400 has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the second dielectric layer 502. For example, the insulation encapsulation 400 has the Df ranges between 0.001 and 0.02 and the Dk ranges between 3 and 4. Thereafter, a second conductive pattern layer 504 and an under-ball metallurgy (UBM) layer 506 are sequentially formed on the first TIV 200 a, the second TIVs 200 b, the die 300, and the insulation encapsulation 400. In some embodiments, at least a portion of the second conductive pattern layer 504 is directly in contact with the insulation encapsulation, the first TIV 200 a, and the second TIVs 200 b. On the other hand, the second dielectric layer 502 is sandwiched between another portion of the second conductive pattern layer 504 and the insulation encapsulation 400. In some embodiments, when the second conductive pattern layer 504 is adapted to transmit signal from the die 300 to the first feed lines FL1 through the first TIVs 200 a and/or when the second conductive pattern layer 504 is adapted to transmit signal from the die 300 to the second TIVs 200 b, the second conductive pattern layer 504 may be referred to as a second feed line FL2. As illustrated in FIG. 5E, a plurality of conductive terminals 600 are attached to the UBM layer 506.

Referring to FIG. 5F, a signal enhancement layer 508 is formed to cover the second conductive pattern layer 504. In some embodiments, the signal enhancement layer 508 has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the second dielectric layer 502. In other words, the signal enhancement layer 508 and the first dielectric layer 502 are formed of different materials. In some embodiments, the signal enhancement layer 508 may be formed by the same material as that of the signal enhancement layer 106. For example, the signal enhancement layer 508 has the Df ranges between 0.001 and 0.02 and the Dk ranges between 3 and 4. In some embodiments, the second dielectric layer 502, the second conductive pattern layer 504, the UBM layer 506, and the signal enhancement layer 508 may be collectively referred to as a second redistribution structure 500. It should be noted that in some embodiments, the signal enhancement layer 106 may be referred to as a first signal enhancement layer while the signal enhancement layer 506 may be referred to as a second signal enhancement layer.

Referring to FIG. 5G to FIG. 5J, the steps illustrated herein are similar to the steps presented in FIG. 2G to FIG. 2J, so the detailed descriptions thereof are omitted herein. As illustrated in FIG. 5J, since the first feed lines FL1 are wrapped around by the signal enhancement layer 106 and the second feed lines FL2 are wrapped around by the insulation encapsulation 400 and the signal enhancement layer 508, due to the low loss dissipation factor and/or the low permittivity nature of the signal enhancement layer 106, the insulation encapsulation 400, and the signal enhancement layer 508, the signal loss/decay when transmitting through the first feed lines FL1 and the second feed lines FL2 may be effectively reduced. As a result, the signal originated from the die 300 may be coupled to the conductive patches 800 and/or transmitted to the second TIVs 200 b with minimum loss, thereby effectively enhancing the efficiency of the integrated fan-out package 40.

In accordance with some embodiments of the disclosure, an integrated fan-out package includes a first redistribution structure, a die, an insulation encapsulation, and a second redistribution structure. The die is disposed on the first redistribution structure. The insulation encapsulation encapsulates the die. The second redistribution structure is disposed on the die and the insulation encapsulation. At least one of the first redistribution structure and the second redistribution structure includes a dielectric layer, a feed line, and a signal enhancement layer. The feed line is at least partially disposed on the dielectric layer. The signal enhancement layer covers the feed line. The signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the dielectric layer.

In accordance with some alternative embodiments of the disclosure, an integrated fan-out package includes a first redistribution structure, a die, an insulation encapsulation, and a second redistribution structure. The first redistribution structure includes a first dielectric layer, a first feed line, and a first signal enhancement layer. The first feed line is disposed on the first dielectric layer. The first signal enhancement layer covers the first feed line. The die is disposed on the first redistribution structure. The insulation encapsulation encapsulates the die. The second redistribution structure is disposed on the die and the insulation encapsulation. The second redistribution structure includes a second feed line, a second dielectric layer, and a second signal enhancement layer. The second feed line is disposed on the insulation encapsulation and the die. The second dielectric layer is sandwiched between a portion of the second feed line and the insulation encapsulation. The second signal enhancement layer covers the second feed line. The first signal enhancement layer and the second signal enhancement layer have a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the first dielectric layer and the second dielectric layer.

In accordance with some alternative embodiments of the disclosure, an integrated fan-out package includes a first redistribution structure, a die, an insulation encapsulation, and a second redistribution structure. The first redistribution structure includes a dielectric layer and a feed line. The feed line is disposed on the dielectric layer. The die is disposed on the first redistribution structure. The insulation encapsulation encapsulates the die and includes a protrusion laterally wraps around the feed line. The insulation encapsulation has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the dielectric layer. The second redistribution structure is disposed on the die and the insulation encapsulation.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. An integrated fan-out package, comprising: a first redistribution structure; a die, disposed on the first redistribution structure, wherein the die has an active surface and a rear surface opposite to the active surface, and the rear surface of the die is coplanar with the first redistribution structure; an insulation encapsulation encapsulating the die; and a second redistribution structure, disposed on the die and the insulation encapsulation, wherein at least one of the first redistribution structure and the second redistribution structure comprises: a dielectric layer; a feed line, at least partially disposed on the dielectric layer; and a signal enhancement layer covering the feed line, wherein the signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the dielectric layer.
 2. The integrated fan-out package according to claim 1, wherein the signal enhancement layer has the Df ranges between 0.001 and 0.02.
 3. The integrated fan-out package according to claim 1, wherein the signal enhancement layer has the Dk ranges between 3 and
 4. 4. The integrated fan-out package according to claim 1, wherein the signal enhancement layer and the insulation encapsulation are made of a same material.
 5. The integrated fan-out package according to claim 1, further comprising a plurality of first through interlayer vias (TIV) and a plurality of second TIVs embedded in the insulation encapsulation, the plurality of first TIVs electrically connect the first redistribution structure and the second redistribution structure, and the plurality of second TIVs are electrically connected to the second redistribution structure.
 6. The integrated fan-out package according to claim 1, wherein the active surface of the die faces the second redistribution structure, and the feed line extends over the rear surface of the die.
 7. The integrated fan-out package according to claim 1, further comprising a plurality of conductive terminals disposed on the second redistribution structure.
 8. The integrated fan-out package according to claim 1, further comprising: an insulating layer disposed on the first redistribution structure opposite to the die; and a plurality of conductive patches disposed over the insulating layer.
 9. An integrated fan-out package, comprising: a first redistribution structure, comprising: a first dielectric layer; a first feed line disposed on the first dielectric layer; and a first signal enhancement layer covering the first feed line; a die, disposed on the first redistribution structure; an insulation encapsulation encapsulating the die; and a second redistribution structure disposed on the die and the insulation encapsulation, comprising: a second feed line, disposed on the insulation encapsulation and the die; a second dielectric layer, sandwiched between a portion of the second feed line and the insulation encapsulation; and a second signal enhancement layer covering the second feed line, wherein the first signal enhancement layer and the second signal enhancement layer have a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the first dielectric layer and the second dielectric layer.
 10. The integrated fan-out package according to claim 9, wherein the first signal enhancement layer and the second signal enhancement layer have the Df ranges between 0.001 and 0.02.
 11. The integrated fan-out package according to claim 9, wherein the first signal enhancement layer and the second signal enhancement layer have the Dk ranges between 3 and
 4. 12. The integrated fan-out package according to claim 9, wherein the first signal enhancement layer and the insulation encapsulation are made of a same material.
 13. The integrated fan-out package according to claim 9, further comprising a plurality of first through interlayer vias (TIV) and a plurality of second TIVs embedded in the insulation encapsulation, the plurality of first TIVs electrically connect the first redistribution structure and the second redistribution structure, and the plurality of second TIVs are electrically connected to the second redistribution structure.
 14. The integrated fan-out package according to claim 9, further comprising a plurality of conductive terminals disposed on the second redistribution structure.
 15. The integrated fan-out package according to claim 9, further comprising: an insulating layer disposed on the first redistribution structure opposite to the die; and a plurality of conductive patches disposed over the insulating layer.
 16. An integrated fan-out package, comprising: a first redistribution structure, comprising: a first dielectric layer; a ground plane disposed on the first dielectric layer; a second dielectric layer disposed on the first dielectric layer, wherein the second dielectric layer covers the ground plane, and the second dielectric layer has a plurality of trenches; a first feed line disposed on the first dielectric layer and located in the plurality of trenches; and a first signal enhancement layer filled in the plurality of trenches to cover the first feed line and sidewalls of the plurality of trenches, wherein the first signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the first dielectric layer; a die, disposed on the first redistribution structure; an insulation encapsulation encapsulating the die; and a second redistribution structure disposed on the die and the insulation encapsulation, comprising: a second feed line, disposed on the insulation encapsulation and the die; and a second dielectric layer, sandwiched between a portion of the second feed line and the insulation encapsulation.
 17. The integrated fan-out package according to claim 16, further comprising a second signal enhancement layer covering the second feed line, wherein the second signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the second dielectric layer.
 18. The integrated fan-out package according to claim 17, wherein the first signal enhancement layer and the second signal enhancement layer have the Df ranges between 0.001 and 0.02.
 19. The integrated fan-out package according to claim 17, wherein the first signal enhancement layer and the second signal enhancement layer have the Dk ranges between 3 and
 4. 20. The integrated fan-out package according to claim 16, further comprising a plurality of first through interlayer vias (TIV) and a plurality of second TIVs embedded in the insulation encapsulation, the plurality of first TIVs electrically connect the first redistribution structure and the second redistribution structure, and the plurality of second TIVs are electrically connected to the second redistribution structure. 